I recently listened to this, and while I feel differently about it, I can't counter your arguments. As such, this is a good and fair review. The thing is, it's the familiarity that can be part of the attraction, assuming you're predisposed to Glass in the first place. I have a friend who feels as you do, not to put too fine on a point on it, he thinks it all basically sounds the same. Which I guess is the nub of your problem with this piece.
As for Glass being "most important American symphonist", point taken. Glass sure had become a popularist in the field, hasn't he? I find myself playing Reich and Adams more often myself (along with Palestine, Conrad, Niblock). But on the other hand, I just bought the 10 disc Glass retrospective!
In the end I like Glass, it's undemanding in many ways, yet not shallow. But I just wanted to say that while ultimately I disagree with your overall opinion on this disc (I like it and find it worthy), I did find your comments were truthful and fair.